Marine Benthic Diatoms Research Articles

EFFECTS OF METAL AND PETROLEUM HYDROCARBON CONTAMINATION ON BENTHIC DIATOM COMMUNITIES NEAR CASEY STATION, ANTARCTICA: AN EXPERIMENTAL APPROACH1

The effects of metals and petroleum hydrocarbons on benthic marine diatom communities were assessed using a manipulative field experiment at Casey Station, Antarctica. Uncontaminated, metal contaminated, and petroleum hydrocarbon contaminated sediments were deployed for 11 weeks during the 1999 austral summer. The treatments were deployed at three different locations: Brown Bay, which has elevated levels of anthropogenic contaminants, and two uncontaminated reference locations, O'Brien Bay and Sparkes Bay, the latter of which has naturally occurring high concentrations of some heavy metals. At each location, significant differences between the composition of diatom communities recruiting to control and petroleum hydrocarbon contaminated treatments were observed. Navicula directa (Smith) Ralfs occurred at lower abundances in the petroleum hydrocarbon contaminated treatments than in the control treatments. In contrast, Navicula cancellata Donkin occurred at higher relative abundances in both contaminated treatments relative to the control treatment. Interactions between treatment and location were also observed for several species, including Navicula glaciei Van Heurck. Significant differences in the overall community composition of diatom communities between control and metal contaminated treatments and metal contaminated and petroleum hydrocarbon contaminated treatments were only observed within Brown Bay. The location of deployment also had a significant influence on the composition of diatom communities. Brown Bay had higher abundances of Achnanthes brevipes Agardh but lower abundances of Navicula aff. cincta (Ehrenberg) Van Heurck than either reference locations. This experiment demonstrated that benthic diatom communities are sensitive to sediment contamination and would be suitable for future monitoring work within this and other areas of Antarctica.

Influence of temperature on the relationship between oxygen- and fluorescence-based estimates of photosynthetic parameters in a marine benthic diatom (Cylindrotheca closterium)

In this paper we investigate the temperature sensitivity of the photosynthetic process of the benthic diatom Cylindrotheca closterium grown in light-limited turbidostat cultures at two different growth rates. Photosynthesis was measured as the rate of oxygen evolution and as the photosystem II (PSII) electron transport rate (ETR). The photosynthetic efficiency (a), as measured by both methods, was rather insensitive to temperature, and decreased significantly only at the extreme temperatures used (5 and 35°C). The maximum PSII quantum efficiency (Fv/Fm) showed a small but significant trend of reduction with increasing temperature. However, the maximum rate of photosynthesis (PB max and ETRmax) was extremely temperature sensitive. The effect of temperature on the relationship between PB and ETR was limited to the most extreme temperatures investigated; deviations from linearity were most extreme at 5°C and different conversion factors were observed at 5 and 35°C. A short-term change in temperature (10–30°C), as might be experienced during emersion on a European tidal flat, will not significantly affect the relationship between PB and ETR. However, care should be taken when using a single conversion factor between PB and ETR at the extremes of the temperature range. We have also shown that algal absorption measurements are important for correct calculation of ETR. The facts that different species seem to have different conversion factors and that changing environmental conditions will affect the absorption capacity and growth rate of the microphytobenthos (MPB) community suggest that it is wise to perform further calibrations of the relationship in the field before use in primary production modelling. Variable fluorescence measurements are quick and non-invasive and, with knowledge of the absorption properties of the MPB community, allow the quantification of photosynthetic parameters across large areas. Hence they are potentially useful for improving our estimates of ecosystem scale primary production.

The effect of agricultural fertilizer on growth rate of benthic diatoms

The aim of this work was to consider a non-conventional medium for benthic diatoms culture, formulated with liquid agricultural fertilizers and with the ‘f/2’ medium used as control. Three strains of benthic marine diatoms ( Nitzschia laevis, Nitzschia thermalis var. minor and Navicula incerta) were grown with these two media, in batch cultures in 18-l plastic containers. There were no significant differences in mean cell concentration and growth rate between three diatoms raised with agricultural fertilizers compared to the standard ‘f/2’ medium. The cost for non-conventional culture media is less than 1/8 the cost of the ‘f/2’ medium.

Natural vs. human-induced facies changes in recent, shallow fjord sediments of the Store Lungegårdsvannet in Bergen (western Norway)

A basin-wide change from an older homogeneous bioturbated to a younger laminated facies occurs in sediments from the 26-m-deep, permanently anoxic Store Lungegardsvannet fjord. The younger facies consists of alternating packages of light and dark layers, each containing millimetre-scale laminae. The composition of the dark layers differs from that of the light layers in the occurrence of predominantly marine benthic diatoms, larger grain size, lower loss-on-ignition (LOI) and lower trace metal (Cu, Pb, Zn) concentrations. Total trace metal concentrations correlate with the redox-sensitive trace elements Mo and V (r>0.8) and with LOI (r=0.6). The correlation of the minerogenic matter and the grain-size related elements Al and Li is poor (r=0.2). The shoaling of the sill depth and reduction of the fjord area resulting in the reduction of bottom water exchange accounted for the shift from bioturbated to laminated sediments during the end of the last century. The alternating changes within the laminated facies are the result of alternating wind forces. During years of calm wind conditions (1908–1919 and 1945–1961), undisturbed sedimentation of organic matter from primary production and an associated accumulation of trace metals prevail. Years of high wind force (1919–1945 and 1961–1991) trigger shore erosion and an increased influx of minerogenic matter.

Sediment toxicity tests using benthic marine microalgae Cylindrotheca closterium (Ehremberg) Lewin and Reimann (Bacillariophyceae)

A new method for sediment toxicity testing using marine benthic pennate noncolonial diatom ( Cylindrotheca closterium, formerly Nitzschia closterium) has been developed. This microalgae showed a good growth rate during the experimental period, even when low enriched media were used. Sediment spiked with heavy metals [cadmium (Cd), copper (Cu), and lead (Pb)] was employed to determine the EC 50 values, using microalgal growth inhibition as the endpoint. The obtained results were as follows: Three heavy metals (Cd, Cu, and Pb), previously spiked on experimental sediment, were separately assayed in toxicity tests. The EC 50 values for these heavy metals in microalgal growth inhibition tests resulted to be 79 mg kg −1 for Cd, 26 mg kg −1 for Cu, and 29 mg kg −1 for Pb (in experimental sediment). The influence of sediment granulometry on the growth of microalgal population was also studied, finding that the growth of the microalgal population on media containing sediment with a relation sand-size:silt size of 9:1 was not different from optimal growth (occurring in media containing 100% sand-sized sediment). The diatom C. closterium proved to be a suitable organism for sediment toxicity tests, due to its sensitivity and fast growth even in poorly enriched media.

Induction of larval settlement in the polychaete Hydroides elegans by surface-associated settlement cues of marine benthic diatoms

Larval settlement in the polychaete Hydroides elegans is mediated by marine biofilms, which are complex agglomerates of bacteria, diatoms, fungi and protozoa. The induction of H. ele- gans larval settlement by marine biofilms has been mainly attributed to bacteria and diatoms. In con- trast to bacteria-derived settlement cues, the nature and origin of diatom-derived settlement cues is poorly understood. In this study, we present the first investigation on the nature and origin of larval settlement cues produced by marine diatoms. Diatoms with inductive (i.e. Achnanthes sp. and Nitzschia constricta) and non-inductive (i.e. Amphora tenerrima and N. frustulum) effects on larval settlement of H. elegans were selected as model strains in this investigation. Larval settlement bio- assays with a choice between monospecies diatom films and unfilmed substratum revealed that the diatom-derived settlement cue was water-insoluble and associated with the film surface. There was a clear correlation between the surface coverage of diatoms in films and their inductive effect on larval settlement. In the case of Achnanthes sp., even the lowest surface coverage of 1.8% induced larval settlement significantly more than the control of filtered seawater. The interstitial distance between diatom cells at this low film density was within the body size range of H. elegans larvae (100 ± 30 µm). The inductive effect of diatom films on larval settlement prevailed even after heat treatments (121°C for 1 h) that completely killed the diatoms, as verified with the vital stain fluores- cein diacetate. These results suggest that the induction of larval settlement by diatoms is not related to their viability, and that, contrary to marine bacteria, diatom-induced larval settlement cues are composed of heat-stable surface components, such as capsular extracellular polysaccharides. These results not only demonstrate that different components of biofilms play inductive and inhibitive roles on larval settlement, but also that their relative space occupation deserves consideration regarding their roles as mediators of larval settlement.

실내 수조에 설치한 파판에서의 해양 부착 규조의 단기간 천이 및 출현종

이 연구에서는 패류의 유생 사육용 식물먹이생물로 배양중인 부착규조 팍판 배양 과정에서 부착 기질인 파판에 어떤 종류의 식물먹이생물이 부착, 출현하며 어떠한 천이 과정을 거치는지 검토하였다. 실험은 비닐하우스내의 약 20톤 콘크리트 직사각형 수조에 파판을 설치하여, 수온 <TEX>$8.5{\pm}0.3^{\circ}C$</TEX>, 비중 <TEX>$1.0250\~1.0260$</TEX>, 조도 <TEX>$2,200\~13,000$</TEX> lux의 범위에서 20일간 배양하면서 5일 간격으로 관찰하였다. 각 관찰일에 계수한 시료 중 규조류의 세포 수는 시간이 경과함에 따라 매우 빠른 속도로 증가하였으며, 20일간의 실험 기간중 출현한 식물먹이생물은 모두 10종으로 Navicula sp. cf. viridula, Cylindrotheca closteriua Licmophora sp., Pleurosigma normanii,Bacillaria paradoxa, Asterionella glacialis, Stephanoppis sp. cf. turris, Entomoneis sp., Odontella aurita, Cocconeis sp. of, scutellum가 관찰되었다. 한편 각 관찰일별 출현종 수는 5일째가 2종, 10일째 3종, 15일째 10종 그리고 20일째에는 3종이 관찰되었는데, 20일째에는 15일째에 새로이 출현한 7종이 모두 사라졌다. 한편, 실험기간 중 우점종은 Navicula sp. cf. viridula였다. We observed the succession and appearence species of the marine benthic diatoms for the effective seed production of shellfish culture on wave plates in indoor mass culture tanks. Every five days, the existence species and densitiy of diatoms were counted during the 20 culture days. Experimental conditions were 8.5 <TEX>$\pm$</TEX> 0.3<TEX>$^{\circ}C$</TEX> of water temperature, 1.0250<TEX>$\~$</TEX>1.0260 of specific gravity, 2,200<TEX>$\~$</TEX>13,000 lux of light intensity. The total density of appearence species was rapidly increased with the lapse of time. However, the number of appearence species decreased on the 20th day. The diatoms observed were 10 species; Navicula sp. of, viridula, Cylindrotheca closterium, Licmophora sp., Pleurosisma normnii, Bacillaria Paradoxa Asterionella glacialis, Stephanopuis sp. cf, turris, Entomoneis sp., Odontella aurita and Cocconeis sp, cf, scutellum. Of them, Navicula sp, of, viridula was most dominant throughout the experiment.

Oxygenic photosynthesis as driving process in exopolysaccharide production of benthic diatoms

The secretion of exopolysaccharide in an axenic culture of the marine benthic diatom Cylindrotheca closterium was investigated. The central question of the experiments was if polysaccharide secretion was dependent on light and photosynthesis. Cells were incubated in the Light, in the dark, or in the light with addition of the inhibitor of Photosystem II, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU). These treatments were also applied to a population of benthic diatoms on an intertidal mudflat in the Westerschelde (Scheldt estuary, The Netherlands). In the light (60 mu mol photons m(-2) s(-1)) C, closterium showed high rates of polysaccharide secretion, while no secretion was observed in the dark or in the presence of DCMU. No intracellular carbohydrate was converted to exopolysaccharide in the dark or in the Light with DCMU added. This indicated that secretion of exopolysaccharide was dependent on oxygenic photosynthesis. Similarly, high rates of exopolysaccharide accumulation were observed during daytime emersion on the mudflat, but not in darkened or DCMU-treated sediment. This demonstrated that the pattern observed in cultures of C, closterium was reproducible in situ. It was observed that during daytime emersion patterns of vertical migration in the dark and DCMU-treated plots did not differ from those in the light. This implies that motility was not the steering factor for the observed accumulation of exopolysaccharide in the Light. When an axenic culture of C. closterium was incubated under an alternating 12 h Light:12 h dark cycle, exopolysaccharide concentrations decreased in the dark. Degradation of exopolysaccharide was also observed in the natural population on the mudflat during emersion at night. Because no bacteria were present in the C, closterium cultures, it was conceived that the degradation of exopolysaccharide observed in cultures was due to secretion of hydrolytic enzymes by C, closterium. [KEYWORDS: Cylindrotheca closterium; diatoms; exopolysaccharide; extracellular polymeric substances; intertidal sediments; microphytobenthos; photosynthesis; polysaccharide Intertidal cohesive sediments; epipelic diatoms; chlorophyll-a; erodibility; adhesion]

Benthic marine diatom deformities associated with contaminated sediments in Hong Kong

Three thousand benthic diatoms were examined at each of twelve sites to determine the frequency of diatom deformities. Two basic types of diatom deformities were observed: 1) diatoms with deformed cell wall morphology; and 2) diatoms with deformed valve wall ornamentation. Only six deformed diatoms were observed. Deformed individuals of Fragilaria capucina and Achnanthes hauckiana displayed external cell wall deformities, while deformed individuals of Diatoma vulgare displayed valve walls with a wavy pattern of longitudinal lines in which the valve ornamentation, rather than the valve cell wall, was abnormal. The deformity frequency of Navicula rhyncocephala, Achnanthes hauckiana, Fragilaria capucina, and Diatoma vulgare was significantly lower at unpolluted sites than at polluted sites based on Fisher exact probability estimates. Cadmium reached 1.1 mg/kg dry wt. of sediment, while other levels were chromium (42 mg/kg of sediment), copper (440 mg/kg), nickel (31 mg/kg), lead (130 mg/kg), and zinc (450 mg/kg of sediment) at the most polluted site. There was a significant correlation (P < 0.05, r s = 0.652) between sediment toxicity, as reflected by the Microtox test, and benthic diatom diversity. The most polluted site exhibited the highest Microtox acute toxicity levels, the lowest diversity, and moderate diatom deformity levels. It was concluded that abnormal cell morphology of diatoms may be a valid indicator of ecosystem health. However, because the amount of time and effort required to identify a statistically meaningful number of deformed diatoms is so great, diatom deformity frequency is unlikely to become a useful tool unless an automated system of assessing diatom deformity frequency is developed.

Effects of enhanced UVB radiation on a marine benthic diatom mat

In order to study the ecophysiological response of a natural diatom-dominated microbial mat to an enhanced level of ultraviolet-B radiation (UVBR), intact sediment cores from a shallow microtidal bay on the Swedish west coast were incubated in an outdoor flow-through system and exposed to either no UVBR or to an artificially enhanced level of UVBR. The microbial mat was cohesive and dominated by the large (≈ 400 μm) motile diatom Gyrosigma balticum. Functional response to UVBR was assessed by measuring carbon fixation (14C) and allocation of photosynthetic products. Sediment oxygen microprofiles were measured as indicators of the balance between the photosynthetic and respiratory activity of the community. Structural variables included biomass and composition of microalgae, pigment composition (HPLC), content of UV-absorbing compounds, and composition of fatty acids. An enhanced level of UVBR resulted in significant functional changes in the microalgal community. Significantly decreased carbon fixation and lower net oxygen production (as calculated from oxygen microprofiles) suggest that primary productivity in the type of microbial mat studied is potentially sensitive to an enhanced level of UVBR. The pattern of carbon allocation hinted a change as to the photosynthetically active part of the community when exposed to UVBR, indicating a differential sensitivity among algal cells. Despite significant functional effects, pigment or algal composition were not significantly affected by enhanced UVBR. The concentration of UV-absorbing compounds was low and did not increase at UVBR exposure. Due to the short duration of the experiment (4 d), a change in algal biomass or composition was not to be expected. Moreover, the thickness of the sampled sediment layer, may have contributed to the lack of observed structural effects of enhanced UVBR. Visual observations suggested that UVBR affected the motility of G. balticum. This study, as well as other experiments with a similar diatom mat, suggest that vertical migration is a key mechanism to be further studied in relation to UVBR exposure of diatom-dominated microbial mats.

海産付着珪藻の分類と生態

海産付着珪藻の分類と生態

Diatoms in recent Atlantic (20� S to 70� N latitude) sediments: abundance patterns and what they mean

Valve abundances of marine planktonic, marine benthic and freshwater diatoms in 780 sediment surface samples from the North and Equatorial Atlantic between 20° S 75° W and 70° N 10° E display patterns that do not correspond to published records of primary production in the photic zone. On the contrary, their abundance is more closely related to dissolution and dilution by terrigenous minerogenic and biogenic carbonate material. Highest abundances of marine planktonic diatoms occur in the northern North Atlantic south of Iceland and in the equatorial regions. The central North Atlantic and the central Caribbean, which feature lower primary production in the photic zone, contain few or no diatoms in surface sediments. African derived freshwater diatoms are concentrated in a lobe between 5° S and 20° N latitude decreasing in numbers from the African continent westward.

The genus Thalassiosira (Bacillariophyta): T. cedarkeyensis, a new marine benthic diatom from the Florida coast of the Gulf of Mexico

Abstract A new diatom species, Thalassiosira cedarkeyensis, is described associated with artificial reef substrate from Cedar Key waters off the Florida coast in the north-eastern Gulf of Mexico. T. cedarkeyensis can be differentiated by its extremely small cells (7.5–9.5 μm in diameter), tangentially undulated valves, restriction of occluded processes and the distal end of the rimoportula to the convex part of the valve, the presence of a marginal ring of fultoportulae and a single subcentral fultoportula, each process with four satellite pores and four struts. The epicingulum is composed of 5–6 open, perforated bands, whose openings are offset to the right (dextral symmetry). The valve mantle is bordered by a hyaline vertical rim and is 3 areolae high. The new species is compared with morphologically similar forms. The present report is the first record of a plicated species of Thalassiosira from the Gulf of Mexico.

Habit, frustule morphology and distribution of the antarctic marine benthic diatomEntopyla australisvar.gigantea(Greville) Fricke (Entopylaceae)

The Antarctic marine benthic diatom Entopyla australis var. gigantea (Grev.) Fricke was collected as an epiphyte on red algae at Anvers Island, Antarctica. Cells of E. australis var. gigantea form ribbon-shaped colonies, and the sibling cells are attached by means of mucilage extruded through the apical pore fields of concave valves. No interlocking marginal spines were found in this SEM study. The cingulum is composed of a series of many open bands with elaborations of ligulae (described as rudimentary septa in the literature) at the poles. Each band has a single row of slits at the advalvar margin of the pars interior. The heterovalvate frustule is flexed in girdle view. Valves have simple multiseriate striae arranged alternately on the two sides of the zigzag sternum, but pronounced marginal ridges are seen only in the convex valve. Concave valves have prominent apical pore fields, whereas the convex valves do not. Rimportulae present on both the valves follow the “one per pole” pattern, but differ in ...

CARBON FIXATION IN CULTURED MARINE BENTHIC DIATOMS1

ABSTRACTThe enzyme activity of ribulose 1, 5‐bisphosphate carboxylase‐oxygenase (RuBisCO) and phosphoenolpyruvate carboxylase (PEPC) was measured in four species of marine benthic diatoms isolated from subtidal sediments of Graveline Bayou, Mississippi. Enzyme activities were measured in cultures of Amphora micrometra Giffen, A. tenerrima Aleem and Hustedt, Nitzschia fontifuga Cholnoky, and Nitzschia vermicularis Grunow that were grown at light levels supporting μmax and at light‐limiting irradiances. All four species exhibited similar RuBisCO: PEP ratios (range = 1–1.8) at μmax the lowest ratio (0.4) was observed in A. micrometra. Reduced light levels increased PEPC relative to that measured at μmax in two species.Two‐dimensional paper chromatography was used to determine the first products of carbon fixation in A. micrometra After a 15 s incorporation period, the first product of photosynthetic carbon fixation was 3‐phosphoglycerate even though this alga had a PEPC activity that was three times higher than that of RuBisCO. After 30 s, over 50% of the recovered radioactivity was still in this compound. Stable carbon isotope analyses of a mixture of the four pennate diatoms also suggest the predominant carbon fixation pathway in these benthic diatoms was similar to C3 plants.

The shallow-water soft-bottom benthos in lindåspollene, western Norway

The assemblages of marine benthic diatoms from six soft-bottom, sublittoral localities were studied at roughly monthly intervals, from June 1972 to October 1973. A subset of the data, consisting of abundance scores for the 28 dominating taxa, was subjected to classification analysis and non-metric multidimensional scaling. Both methods divided the samples into the same six, fairly distinct groups, corresponding largely to the six sampling localities. Although the localities sampled were situated within the same ‘poll’-system, and were fairly homogeneous as regards depth and sediment characteristics, samples from a particular locality were thus more closely related to each other than were samples from different localities collected on the same day. No clear seasonality in the species composition was evident in the material. Comparison with earlier investigations from similar habitats, revealed few similarities in species composition or ecological preferences of the species encountered.

A Preliminary Checklist of Epiphytic and Benthic Marine Diatoms of Louisiana

A checklist of diatoms collected from the various habitats in coastal salt marshes, estuaries, and nearshore Gulf waters of Louisiana has been compiled for the first time. The checklist includes 193 taxa (species and their varieties) in 38 genera. The largest numberof taxaarespeciesof,A/aulculaand,Nitzschiawith46and36,respectively. Futurestudies ofthe varied habitats along the Louisiana coast shouid result in many new additions to this preliminary checklist. author were not included in Kalinsky's (1983) checklist. An up-to-date list of diatoms in Louisiana's coastal environments was thought to be needed. In light of the reports of Wood (1963) and Medlin (1983) for Texas, and Sullivan (1981) for Mississippi, the present checklist contributes to our knowledge of the geographic distribution of marine

Antifouling agents against the benthic marine diatom,Navicula salinicola Homarine from the gorgoniansLeptogorgia virgulata andL. setacea and analogs

At concentrations found in the gorgonian corals,Leptogorgia virgulata (L.) andL. setacea (L.), homarine (N-methyl-2-carboxypyridine) and water-soluble extracts from the gorgonians that contained homarine inhibited the growth of the potential fouling diatom.Navicula salinicola Hust., by 50-60%. Homarine comprised 0.3 and 0.25% of the fresh weight ofL. virgulata andL. setacea, respectively, and the water-soluble extracts comprised 4.0 and 3.0% of the fresh weight of the gorgonians, respectively. Three compounds structurally related to homarine including, in order of most to least active, nicotinic acid, picolinic acid, and pyridine, also reduced growth ofN. salinicola. The activity of these compounds in the diatom assay suggests that the carboxyl group at the 2 position of the pyridine ring is important for activity and thatN-methylation is not important. We conclude that chemical defense against fouling is operative inLeptogorgia species. Evidence from the literature for combined chemical and mechanical defenses byLeptogorgia and other organisms against fouling is presented.

The shallow-water soft-bottom benthos in lindåspollene, western Norway

The marine benthic diatoms in a soft-bottom substrate have been studied for about one year at six stations. Diatoms from the uppermost 5 mm of the sediment have been counted. Statistical analyses confirm that there are differences in the number of diatoms from station to station, and also differences in time within stations. The results indicate that most localities have a more or less prominent spring peak and for some stations also a late autumn maximum. Number of diatoms per mm3 varied from about 200 individuals (Stn 5) to about 2000 (Stn 6). Living diatoms were found down to about 16 cm in the sediment, even when there was some hydrogen sulphide at this depth at some of the stations. Arguments are presented for the importance of grazing as a controlling factor of diatom standing crop.

A Preliminary Checklist of Marine Benthic Diatoms of Mississippi

A checklist of diatoms collected from various benthic habitats in coastal salt marshes and offshore seagrass beds of Mississippi has been compiled for the first time. The checklist includes 213 taxa (species and their varieties) in 43 genera with 19 of these taxa found only on the leaves of offshore seagrasses. Synedra fasciculata var. intermedia (Grun.) Sulliv. comb. nov. is proposed to be consistent with the nomenclature of the nominate variety. Future work with this ecologically important group of marine algae should result in many new additions to this preliminary checklist.